Perhaps you should try some spelling variations:
hieu viec » nhieu viec, hieu ve, sieu viet
viec cac » vien cac, viec cua, viec lam
toc sach » hoc sach, doc sach, thuoc sach
thi hang » thi hanh, thi nang, thi hong
hang cho » sang cho, hang khoa, phong cho
thuc van » thuc vat, thuc dan, thuc va
cac thuc » cach thuc, cac thu, can thuc
van anh » van thanh, tuan anh, van minh
cho hoc » co hoc, khoa hoc
anh vi » hanh vi, anh va, anh ve
vi sua » va sua, vi su, vi lua

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: ((te sach) OR (toc sach)) thi hang cho hoc. hieu viec cac thuc van anh vi sua (chua* or cua*)~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) thi hang cho hoc. hieu viec cac thuc van anh vi sua (chua* OR cua*).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) OR (toc sach)) thi hang cho hoc. hieu viec cac thuc van anh vi sua (chua* or cua*)".
• Adding a wildcard symbol may retrieve word variants: ((te sach) OR (toc sach)) thi hang cho hoc. hieu viec cac thuc van anh vi sua (chua* or cua*)*.